Am 2020-04-03 14:44, schrieb Colin Ian King:
Hi,
Static analysis with Coverity has found an issue with the following
commit:
From a092ab25fdaa445b821f5959e458350696fce44c Mon Sep 17 00:00:00 2001
From: Michael Walle <michael@xxxxxxxx>
Date: Fri, 6 Mar 2020 22:44:31 +0100
Subject: [PATCH] tty: serial: fsl_lpuart: fix DMA mapping
The analysis report is as follows for function lpuart_dma_rx_free in
source drivers/tty/serial/fsl_lpuart.c :
var_compare_op: Comparing chan to null implies that chan might be null.
1234 if (chan)
1235 dmaengine_terminate_all(chan);
1236
Dereference after null check (FORWARD_NULL)
var_deref_op: Dereferencing null pointer chan.
1237 dma_unmap_sg(chan->device->dev, &sport->rx_sgl, 1,
DMA_FROM_DEVICE);
The check for chan being null implies it is may be null, however, the
call to dma_unmap_sg dereferences chan which leads to a null pointer
dereference issue.
Technically, this is correct. But lpuart_dma_rx_free() is guarded by
lpuart_dma_rx_use which is only true if there is a dma channel, see
lpuart_rx_dma_startup(). In any way, this looks bogus.
So actually, the "if (chan)" is superfluous. Could you double check
that?
Then I'd make a patch which removes the if (chan) to make coverity
happy.
-michael
